The hydrothermal gasification of opium alkaloid wastewater was investigated in a batch autoclave at 400, 500, and 600 degrees C at a pressure range of 23.0-45.5 MPa without and with various amount of K2CO3 catalyst. The maximum gas yields, hydrogen and methane, were obtained at 600 degrees C using K2CO3 at amounts higher than 0.375 g. TOC and COD contents of the aqueous products and raw wastewater were analyzed, the compounds existing in the raw wastewater and the aqueous products were identified and compared. The wastewater used in this work has a COD content of 35,000 mg O-2/L and a TOC content of 15,000 mg/L and the highest COD removal efficiencies acquired was 95% at 600 degrees C and in the presence of K2CO3 (varying from 0.375-0.625 g). The H-2 and CH4 yields were maximized at 47.7 and 34.3 mol/kg OC in wastewater using 0.5 g of K2CO3 and at 600 degrees C, respectively.